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A Brief History of Chemistry • • • • • Ancient Greece ~_____ BCE ____________ Atomos-_________ Thought matter was discreet A Brief History of Chemistry • Aristotle • Thought matter was ________________ • Credited with 4 Greek elements • Earth • Air • Fire • Water A Brief History of Chemistry • The Middle Ages • ________________ • Europe-Convert base metals to ________ • Asia- ____________ A Brief History of Chemistry • Robert Boyle • The Skeptical Chemist • The beginnings of chemistry as an _________________ _________________ A Brief History of Chemistry • Antoine Lavoisier • The father of modern chemistry • Law of ______________ of Mass • Helped develop the ____________________ • Made first comprehensive list of _______________ A Brief History of Chemistry • John Dalton • _________________ • 1803-1807 A Brief History of Chemistry • 1867 • Dmitri Mendeleev • _________________ A Brief History of Chemistry • 1897 • J. J. Thomson • Discovers ______________ A Brief History of Chemistry • • • • 1911 Ernest Rutherford Gold Foil Experiment Discovered __________________ • Discovered __________ in 1919 • James Chadwick discovered the _______________ in 1932 A Brief History of Chemistry • The Manhattan Project • 1940’s • The Atomic Bomb The Law of Conservation of Mass • Matter is neither _________ nor _________ during chemical reactions or during physical changes. The Law of Definite Proportions • A chemical compound contains the same _________ in exactly the same _________________ by mass regardless of the _________ of the sample or _________ of the compound. The Law of multiple Proportions • If two or more different compounds are composed of the __________________, then the ratio of the masses of the second element combined with a certain mass of the first element is always a ratio of __________________. Dalton’s Atomic Theory • All matter is made up of _______________ called atoms. • Atoms of a given element are identical in ______, ______, and other properties. • Atoms of different elements _______ in size, mass, and other properties. Dalton’s Atomic Theory • Atoms cannot be _________, _________, or _________. • Atoms of different elements can combine in simple, _________________ to form chemical compounds. Dalton’s Atomic Theory • In chemical reactions (rxns), atoms are _________, _________, or _________. Modern Atomic Theory • All matter is composed of __________________particles called atoms. • Atoms of the same element have the same chemical properties, while atoms of different elements have different __________________. Modern Atomic Theory • While individual atoms of a given element may not all have the same _________ (due to differences in nuclear structure), any natural sample of the element will have a definite __________________that is characteristic of that element as compared to any other element. Modern Atomic Theory • _________ are formed when atoms of 2 or more elements unite, with each atom losing its characteristic _________ as a result of this combination. • Atoms are not _________ in physical or chemical rxns. Discovery of the Electron • 1897 • JJ Thomson • Cathode Ray Tube Experiment • Discovered the electron Discovery of the Electron • Air was evacuated from the tube and an electric current was passed through it. • A _________was seen. • When Thomson held a magnet to the glow, it was _________________ the magnet. Discovery of the Electron • This meant that the glowing field had an _________________. • Thomson had to work out whether the glow was _________________. • He placed a ________________ inside of the tube. Discovery of the Electron • If the wheel moved, the glow was __________________. • If the wheel did not move, the glow was _________. • The wheel moved, so Thomson knew that ____________________ _______were produced by the current. Mass of the electron • • • • • 1909 Robert Millikan Oil Drop Experiment Mass of electron 9.109 x 10-31kg Plum Pudding Model Rutherford’s Gold Foil Experiment • • • • 1911 Ernest Rutherford Gold Foil Experiment Discovered the atomic nucleus The atom • An atom is the smallest particle of an element that retains the _______________ of that element. • The ___________ is a very small region located at the center of an atom. • The nucleus is made up of at least one positively charged particle called a ___________ and usually one or more neutral particles called ___________. The atom • Surrounding the nucleus is a region occupied by negatively charged particles called ______________. • Protons, neutrons, and electrons are often referred to as _______________________. Properties of Subatomic particles Forces in the Nucleus • When two protons are extremely close to each other, there is a _______________ between them. • A similar attraction exists when _______ are very close to each other or when protons and neutrons are very close together. • The short-range proton-neutron, protonproton, and neutron-neutron forces that hold the nuclear particles together are referred to as _________________. Nuclear Forces Atomic Number • Atoms of different elements have different numbers of __________. • Atoms of the same element all have the _______ number of protons. • The atomic number (Z) of an element is the number of _________ of each atom of that element. Mass Number • The mass number is the total number of _________________ that make up the nucleus of an isotope. Isotopes • Isotopes are atoms of the same element that have different __________. • The isotopes of a particular element all have the ________ of protons and electrons but _________ numbers of neutrons. • Most of the elements consist of ________ of isotopes. Relative Atomic Mass • The standard used by scientists to compare units of atomic mass is the ______________ atom, which has been arbitrarily assigned a mass of exactly 12 atomic mass units, or 12 amu. • One __________________, or 1 _____, is exactly 1/12 the mass of a carbon-12 atom. • The atomic mass of any atom is determined by comparing it with the mass of the ___________ atom. Average Atomic Mass • Average atomic mass is the weighted average of the atomic masses of the naturally occurring _________ of an element. • Calculating Average Atomic Mass • The average atomic mass of an element depends on both the _______ and the ___________________of each of the element’s isotopes. The mole • A mole (abbreviated mol) is the amount of a substance that contains as many particles as there are atoms in exactly _______ of carbon-12. • The mole is the SI unit for amount of ___________. • Avogadro’s number—6.022 1415 × 1023—is the number of particles in ___________ of a pure substance. Molar Mass • The mass of __________ of a pure substance is called the molar mass of that substance. • Molar mass is usually written in units of _______. • The molar mass of an element is numerically equal to the atomic mass of the element in _________________. Molar Conversions • What is the mass in grams of 3.50 mol of the element copper, Cu? Molar Conversions • How many moles of silver, Ag, are in 3.01 1023 atoms of silver?